Dual firing rate house heating oil burner



March 15', I949. J. A. LOGAN DUAL FIRING RATE' HOUSE HEATING OIL BURNER 4 Sheets-Sheet 1 Filed D90. 10, 1946 m 1 m 0 w & m Jm N 1 1 M 5 Q 4 fl w w w a a w w m 4 w N 2 T w a 3... 1!. IHH

|| i r I m March 15, 1949. J. A. LOGAN 2,464,699

DUAL FIRING RATE HOUSE HEATING on. BURNER Filed Dec. 10, 1946 i 4 sheets-sh et 2 L J 4 a? L 1 P 2 J INVENTOR 1 Jaszp/r A. Lam/v Y a r I ATTO EYS March l5, 1949. J. A. LOGAN 2,464,699

DUAL FIRING RATE HOUSE HEATING OIL BURNER Filed Dec. 10, 1946 4 Sheets-Sheet 3 ATTOR EYS 4 Sheets-Sheet 4 ,INVENTOR wan/14.460 44 y ATTQR EYS J. A/LOGAN DUAL FIRING RATE HOUSE HEATING OIL BURNER.

March 15, 1949.-

Flled Dec 10, 1946 f Patented Mar. 15, 1949 DUAL FIRING RATE HOUSE HEATING on. BURNER Joseph A. Logan, Hadley, Mass, assignor to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a. corporation of Massachu- Se'tts Application December 10, 1946, Serial No. 715,163

7 Claims. 1

This invention relates to improvements in oil burners of the oil pressure atomizing type, which are adapted for heating houses and for intermittent operation at any one of two or more different firing rates, as. may be selected manually or automatically by any suitable controlling means, to change the heating rate as changes in weather conditions occur.

One object of the invention is the provision in a burner of this type in which one nozzle is selected for operation and operates intermittently on and ofi while another ordinarily remains idle, of improvements which provide for frequent operation for short periods of the nozzle that is not selected for operation, in order to keep that nozzle in operating condition and avoid stoppages which might otherwise occur, as will be explained.

Another object of the invention is to provide in a burner adapted for intermittent firing at difierent rates as selected by automatic control or remote manual control, emergency means manually operable in case one nozzle fails, to change over to the other nozzle and temporarily render the automatic or remote control selector means inoperable until a service man is available to correct the trouble.

These and other objects and advantages will best be understood in connection with the description of examples of the invention in connection with the accompanying drawings, in which Fig. 1 is a diagrammatical view of an oil burner embodying the invention and adapted for hand control of the firing rate;

Fig. 2 is a similar view of a burner embodying the invention and adapted for automatic or remote manual control of the firing rate with an emergency hand-operable firing-rate control at the burner for use when the automatic means is disabled or not desired;

Fig. 3 is a cross sectional view of the burner showing a mounting for the motor, fan and pump of the burner and the means for controlling the rate of air flow to the burner;

Fig. 4 is a fragmentary sectional elevational view taken centrally through the air tube of the burner and showing a mounting for the nozzles, ignition electrodes and burner thermostat switch;

Fig. 5 is a cross sectional view taken on the line 55 of Fig. 4; and

Fig. 6 is a fragmentary sectional view taken on the line 6-6 of Fig. 5.

Referring to these drawings and first to Fig. 1 thereof, the burner includes two oil pressure atomizing nozzles I and 2, which are mounted side by side near the outlet endfl of the air tube 4 of the burner. These nozzles I and 2 have different capacities and may, for illustration, be assumed to have the respective capacities of one and two gallons per hour. They are supplied with oil at 6 relatively high pressure by a pump 5, which draws in oil from a pipe I5 and forces it outwardly through a valve I to an outlet conduit 8. Valve 7 opens to allow flow to conduit 8 only after the oil has been placed under a predetermined minimum pressure, say for example, 85 pounds per square inch. Between the pump 5 and valve 1 is a valve 9 which opens, when the pumped oil attains a predetermined maximum pressure, say 100 pounds per square inch, to allow oil to flow through a by-pass I back to the suction side, of pump 5. The nozzles I and 2 are adapted to be connected to the pump alternately. This is effected by a sleeve valve II rotatably mounted within a casing I2. The conduit 8 has a branch The sleeve valve is adapted to be turned by a handle I back and forth through a half revolution between two positions, in one of which a port I6 in the sleeve valve connects with a conduit I1 and in the other of which a port I8 in the sleeve valve connects with a conduit I9. The conduits I1 and I9 connect through separate chambers and 2i in a valve casing 22 with conduits 23 and 24 which connect with the nozzles I and 2, respectively. With the parts positioned as shown, oil will be supplied to the low rate nozzle I by way of conduits 8, I3, chamber I4, port I6, conduit Il, chamber 20 and conduit 23. If the sleeve valve II is turned by its handle I5, 180 from the position shown, the port I6 will move out of register with conduit I! and cut off the flow to nozzle I and the port I8 will connect with conduit I9 to permit oil to flow to the high rate nozzle 2 by way of conduits 8 and I 3, chamber I4, port I8, conduit I9, chamber 2I and conduit 24, the latter including a non-return valve 25, also marked VC, for a purpose to be later described. Thus, oil may be supplied to either nozzle I or 2 to secure firing of the burner at relatively low or relatively high rates respectively.

Air for combustion is supplied by a fan 26 (see also Fig. 3). located within a. housing 21, the outlet of which is connected to the inlet end of air tube 4. Air enters the fan through the central axial opening 28, which is controlled by a shutter 29, located within a hollow housing 30, having air inlets 31. The shutter is adjustable by means of a screw 32 to vary the eflectlve area of the intake to the fan for low firing rate operation. This 56 screw passes through a cylinder 83 and has fixed I3 leading to a chamber I4 inside the sleeve valve.

thereon a piston 34. A spring 35 draws screw 32 inwardly as far as permitted by the abutment of the head of the screw with the outer head of cylinder 33. By admitting fluid to the cylinder, piston 34 will be moved outwardly, bodily moving screw 32 and shutter 29 to increase the eflective area of the air inlet to the fan for high firing rate operation. The high rate position of the shutter is controlled by a stop such as a pin 33 (Fig. 3)

eccentrically located on a screw 31, threaded into,

casing 33. By turning this screw, the high rate position of the shutter 29 may be adjusted with precision. It will be obvious that the described arrangement may be reversed so that the spring will hold the rod 32 against stop 35 in high firing diagrammatically in Fig. 1. This motor is started and stopped under the control ofthe customary room thermostat switch 39. The latter controls a low voltage circuit which is supplied by a transformer, and which includes in series the transformer secondary 43, wire 46, switch 39, wire 4!, the coil 42 of a relay and wire 44. The primary 45 of this transformer is connected by wires 46 and 41 to wires 48 and 49, which connect with a suitable supply source of alternating current. One terminal of the relay switch 50 is connected by wire 5| to supply wire 49 and the other terminal is connected by a wire 52 to one side of motor 38, the other side of the latter being connected by a wire- 53 to supply wire 49. Connected by wires 54 and 55 to motor wires 52 and 53, respectively, is the primary 55 of a suitable ignition transformer. The secondary 51 of the latter is connected by wires 58 and 59 to ignition electrodes 69 and SI. Thus on a call for heat, thermostat switch 39 will close the low voltage transformer circuit, supplying current from secondary 43 to energize the relay coil 42 and cause switch 50 to close. This will start motor 38, set the fan 26 and pump 5 in operation, and energize the ignition transformer to produce ignition sparks at the electrodes 63 and 6!. Oil will be supplied to one nozzle or the other, according to the position of valve H, and will be emitted in an atomized spray to mix with air supplied by the fan through tube 4. The combustible mix- 'ture will be ignited by a spark between the electrodes 68 and 5! For controlling the movement of air shutter 29 to vary the air supply as the oil supply is varied, the described cylinder 33 is connected by a conduit 62 to the conduit 23 which supplies the high 1 rate nozzle 2. Thus, when oil is supplied to the latter, oil will also be supplied to cylinder 33 to move piston 34 as described, and move the shutter 29 to its high rate position against the tendency of spring 35 to keep it in the low firing rate position. This pipe 52 is also connected by a pipe 63 to valve casing 22 and through the latter to a pipe 64 which connects to valve casing l2. The sleeve valve H has a chamber 65 therein with a port 66, which connects with conduit 54, and a port 61, which connects with a conduit 68 leading to by-pass l and thus to the suction 'side of pump 5. With valve H positioned .as shown, the cylinder 33 is connected to the suction side of pump to insure that the piston 34 and shutter the same time, port I8 is moved into register with conduit 19 to supply oil to nozzle 2 and port l6 is moved out of register with conduit [1 to cut off the supply of oil to the low rate nozzle I.

In the practical operation of a burner, such as described, the firing rate selector ll may remain in one position for long periods, during which one nozzle will remain idle and the other nozzle will 29 is in or moves back to low'rate position urged work intermittently under control of the thermostat. It is not desirable to have one nozzle remain idle for too long a period as it tends to clog under the conditions of such idleness. Therefore, to overcome this difficulty, this invention provides means for operating that nozzle, which is not selected by the rate selector means I l,'once during each cycle of operation of the burner to thereby keep it from being idle too long. As herein arranged, if the valve 1 l is set for low rate firing, the burner will start up with high rate firing, which will continue for a short interval, after which low firing rate operation will ensue. Similarly, if the valve II is set for high firing rate operation the burner will start up at the low firing rate and low firing rate operation will continue for a short interval after which high rate operation will ensue. Thus. it is insured that each nozzle will operate each time the burner starts, the nozzles alternating so that one operates only for a short nozzle-conditioning interval during each burner cycle and the other operates for the balance of each such cycle.

To effect the results described, two valves are provided within the casing 22, each being held by a spring in its illustrated position and moved to its other position by a solenoid. One such valve comprises iwo interconnected and axially spaced discs 69 and 10, actuated by its solenoid I I The other comprises two axially-spaced and interconnected discs 12 and I3, aciuated .by its solenoid It. One or the other of these solenoids is connected in circuit so as to be actuated whenever the motor 38 is started. This is effected by means of a switch connected to the firing rate selector II. This switch comprises a metal annulus'l5, fixed to an insulating disc 16, which in turn is fixed to the stem of valve II. A brush ll rides on one face of the annulus 15. The latter has a radial projection 18 to engage one or the other of two stationary contacts 19 or 80, according to the position of the valve II. The brush I1 is connected by a wire 8i to motor wire 52. The contacts 19 and are respectively connected by wires 84 and 83 to one terminal of solenoids 'H and 14. The other terminals of the solenoids II and are respectively connected by wires 85 and 86 to a wire 81 which is connected to one terminal 88 of a switch. The other terminal 89 of this switch is connected by a wire 90 to the motor wire 53. The switch terminals 88 and 89 are connected together when the motor 38 is energized and they are disconnected after the motor has been in operation for a short time.

This may be accomplished by the action of a thermostat 9|, which may for example respond to the heat of combustion and disconnect the contacts 88 and '89 after combustion occurs and con- .nect them together again after combustion ceases.

on the firing rate selector ll. As shown, solenoid II is connected in circuit by the rate selector switch and will be energized when motor 38 is started-the circuit being traced as follows-from wire 52 by wire 8|, brush I1, annulus I5, projection I8, contact 19, wire 84, solenoid ll, wires 85 and 81, contacts 88 and 89, and wire 80 to motor wire 53. When the rate selector is turned to its other position, contact I9 will be disengaged from projection 18 and the circuit to solenoid II will be broken. Projection I8 will then engage contact 80 and establish a circuit to solenoid I4, which circuit is as follows-from wire 52 by wire 8|, brush 'I'I, annulus I5, projection I8, contact 80, wire 83, solenoid I4, wires 88 and 81, contacts-88 and 89, and wire 90 to motor wire 53. The circuit. established to either solenoid will be broken after a predetermined interval by the separation of contacts 88 and 89 under the action of the burner thermostat 9|.

Assuming that the firing rate selector II is set for low rate operation as shown, solenoid II will be energized as soon as the motor 38 starts and the connected valve discs 89 and .10 will be moved to the left and held there momentarily. The disc 89 will block the passage of oil from conduit I1 to conduit 23 and thus prevent operation of the low rate nozzle I. Disc I0 will block cornadvantage of this arrangement is its action in avoiding failures in burner operation due to stoppage of a nozzle or nozzle teed pipe. In the practical use of a dual firing rate burner, the weather conditions may necessitate operation intermittently, at only one rate for relatively long periods and frequently for many consecutive days. If

one nozzle is allowed to be idle for long periods bustion produced by the other nozzle. While the air flow has a cooling effect. on the nozzle and its feed pipe, yet the oil is not in motion in the idle nozzle or its feed pipe but remains stationary so that carbonization is more likely to occur. The

munication between suction conduit 84 and conduit 83 and thus disconnect cylinder 33 from the suction side of pump 5. Disc I0 will also uncover one end of a conduit 92, the other end of which connects with conduit 82 and thus with conduit 24. A conduit 93 connects the pump outlet conduit 8 with that space in valve casing 22 that lies between the valve discs 10 and I2. Thus, oil will fiow from conduit 93 into conduit 92 and, dividing, flow to the left by part of conduit 82 to cylinder 33 and to the right by the rest of conduit 82 and thence by part of conduit 24 to the high rate nozzle 2. Oil will be emitted from this nozzle and air will .be supplied by fan 28 at the necessary increased rate due to the opening of shutter 29 hydraulically by the oil admitted to cylinder 33. In a short time, thermostat ill will open the circuit to solenoid II and the valve discs 59 and 10 will move back to their illustrated positions, thereby cutting off the supplyof oil to the high rate nozzle 2 and to the shutter operating cylinder 33, and again connecting the low rate nozzle I to the oil supply and the cylinder 33 to the suction side of pump 5, thereby reducing the air supply to correspond with the reduction in oil supply.

When solenoid I4 is energized, the valve discs 12 and 13 are drawn to the right as far as possible. Disc I3 will then close off communication between the conduits I9 and 24, thereby cutting of! the oil supply to the high rate nozzle 2 and to the cylinder 33. The disc I2 will uncover an opening to a conduit 94, allowing oil to enter and flow through the latter and through conduit 23, to the low rate nozzle I. Thus, the operation of the high rate nozzle 2 will initially be prevented and the low rate nozzle will be operated until the thermostat switch 88, 89 opens. Then, the valve discs 12 and I3 will move back to their illustrated positions, cutting 03 oil fiow to the low rate nozzle I and establishing oil flow to the high rate nozzle 2 and to the cylinder 33 to increase the rate of air supply.

It will be clear that the invention provides for the operation of both nozzles during each cycle of operation of the burner, one nozzle operating for a relatively short portion and the other for the remaining portion of each such cycle. i The invention guards against this trouble by avoiding long periods of inactivity of the nozzle that is not brought into use by the firing rate selector means. The unselected nozzle is made to operate each time the selected nozzle operates although for a shorter portion of the cycle of operation of the burner and this helps to keep the unselected nozzle and its feed pipe in working condition. This is important in house heating apparatus where there is no fireman in attendance to see that the equipment is kept in good order.

The firing rate selector may be automatically operated in response to a thermostat or other suitable control. Such an arrangement is shown. in Fig. 2. The firing rate selector, shown in Fig. 2, differs in detail from that shown in Fig. 1 but it performs the same functions. The solenoid valves are exactly as shown in Fig. 1 and they function in the same way to insure operation of both nozzles I and 2 during each cycle of burner operation, one for a short portion and the other and the electrical connections are the same as in Fig.1 except for the additions presently to be described. Parts in Fig. 2 which correspond with parts in Fig. 1 have been given the same reference numerals and need not be again described.

The firing rat selector, shown in Fig. 2, consists of a slide valve having'two interconnected discs and 98 which are slidable within a casing 91 and normally spring held in the illustrated and low rate position. A solenoid 98, when energized, will move the valve to its other and high rate position. This solenoid 98 is controlled by a thermostat switch 99, which closes and opens accordingly as the temperature at the region wher it is located is respectively below or above a predetermined temperature. The thermostat switch 99 may, for example, be located outdoors and arranged to close when the outdoor temperature v falls so low as to justify operation of the burner at a higher rate. The circuit for the rate selector may be traced as followsfrom supply' wire 49,

. wire I00, thermostat switch 99, wire IOI, solenoid 98, wire I02, a brush I03, a contact I04, a brush I05, and wires I08 and 52, relay switch 59, and wire 5i to supply wire 48. The solenoid 98 will thus be energized by the closing of thermostat switch 99 only after the motor circuit has been closed by relay switch 50, following the closing of room thermostat switch 39. When there is a call for heat, the burner will be started by the closing of the room thermostat switch 39 and then, or

thereafter at any time while the burner is in oporation, if there is a demand for high rate burner operation, the solenoid 98 will be energized by the closing of thermostat switch 99, whereby the selector valve will be shifted to high rate position.

When this selector valve is in low rate position, oil from the pump enters through conduit I3 into casing 91 into the space between the discs 95 and 96 of the slide valve and this space is then connected to the conduit II, which leads as before through space 20 and conduit 23 to low rate nozzle I. At the same time, the air shutter operating cylinder 33 is connected to the suction side of pump 5 by conduits 62 and 63, the space between discs 69 and I0 in valve casing 22, conduit 63, the space to the left of disc 95 in casing 91, and conduits 68 and I0. When the selector valve is shifted to high rate position, disc 95 closes oil communication between conduits 68 and 68 and cuts off the suction connection to shutter-operating cylinder 33. Disc 95 when moved to the left, also enables communication between oil feed conduit I3 and the conduit I9, which enables oil to flow through conduit I9, space 2I' and conduit 24 to the high rate nozzle and also enables oil to fiow through conduit 62 to the cylinder 33. Disc 96 when moved to the left, closes off communication between the oil feed conduit I3 and the conduit I! and blocks operation of the low rate nozzle I.

The solenoid 98 also actuates a switch to cause that nozzle, which is not selected by the automatic firing rate selector means, to be momentarily operated prior to the operation of the nozzle selected by such means. This switch comprises a blade I01 movable back and forth between the contacts I9 and 80 and itself connected to a wire 8|, which is connected to a brush I08, normally connected by a contact I09 to another brush H8, connected to the wire 8I. Blade I01 is engaged with contact I9, when the firing rate selector is set for the low rate, as illustrated. Then, when the motor 38 is started, solenoid II will be energized. The circuit may be traced as followsfrom motor wire 52, by wire 85, brush H9, contact I09, brush I08, wire 8|, blade I01, contact 19, wire 88 to solenoid H and by wires-85 and 81, contact 88, thermostat 9i, contact 89 and wire 90 to motor wire 53. As before, this solenoid will be deenergized in a .predetermined time by the disconnection of the contacts 88 and 89 by thermostat 9|. When the automatic rate selector pump 5 to the high firing rate nozzle2 and also to the hydraulic power cylinder 33 for the purpose of moving the shutter'29 into its high firing rate osition and, when deenergized, to enable the valve to be moved back by its spring into position to connect the pressure side ofpump 5 to the low firing rate nozzle I and the power cylinder 33 to the suction side of pump 5.

With a system, such as described, where the firing rate is automatically selected, it is desirable to provide emergency means to enable hand selection of the firing rate if for any reason one nozzle is rendered inoperative. For example, if

when the thermostat switch 99 closed on a de-' It may also happen that fiow to or through the low rate nozzle I will stop for some reason, while the automatic rat selector valve is set for low rate operation, and it is desirable then to be able to manually shift to high rate firing.

One way of accomplishing the selection by hand of the firing rate and at the same time disconnecting the automatic firing rate selector means is by means of the switch shown. at the right hand part of Fig. 2. This switch comprises three insulating discs III, H2 and H3 which are movable in unison by a handle I I4 from a neutral position, marked N, to the right or left by 90 angles into low rate or high rate positions,

marked L and H, respectively. The inner disc is moved to high rate position, blade I01 will engage contact 80 and solenoid 13 will be energized. The circuit may be traced as follows-from motor wire 52, wire 88, brush H8, contact I89, brush I08, wire 8!, blade I03, contact 80, wire 83 to solenoid I I and thenc by wires 88 and 81,

contact 88, thermostat 9i, contact 89 and wire 90 to the motor wire 53.

The burner may, if desired, be operated without the reversing valves 69, i8, i2 and 83, their actuating solenoids ii and I3, the control switch I01, the thermostat switch 9i and the electrical connections between such switches and solenoids. The pipes 92, 93 and 94 then become unnecessary and the pipes I I, I9 and 54 will be respectively,

HI carries a contact II5, which will engage and interconnect two stationary brushes H6 and Ill, when the switch is in high rate position. These brushes H8 and Ill are respectively connected by wires H8 and H9 to wires 86 and 90. The eifect produced is the short circuiting of the burner thermostat switch 88, 89 so that it cannot, as before, deenergize the solenoid II. The discs H2 and II3 respectively carry the contacts I88 and H09 before described. When disc II2 moves to either low rate or high rate position, the contact I04 dlsengages from the brushes I03 and I05 and opens the circuit to the solenoid 98 of the automatic firing rat-e selector means. At the same time, the contact I09 dlsengages from the brushes I08 and H0 and opens the circuit to the rate selector switch I01. This same contact I08, when disc I I2 is moved to high rate position, will interconnect two brushes I23 and I24, which are connected by wires I25 and I26 to wires I06 and 88, respectively. This will energize solenoid I'II, wire I I9 and up by wire to motor wire 53.

The energization of solenoid II will draw valve discs 69 and I0 to the left. Disc 69 will then cut off flow between conduits I1 and 23 and thus to the low rate nozzle I. Disc 10 will allow oil to flow from conduit 93 into conduit 92 and from the latter to the right by conduit 62 to conduit 2,8 and thus to high rate nozzle 2 and to .the left by conduit 62 to the cylinder 33 to cause the air shutter to be moved to increase the air supply appropriately for high rate firing. The valve discs 69 and I0 will be held in the described posi 9 tion until the motor switch 59 opens by the opening of room thermostat switch 39.

When, the handle H4 is turned to low rate position, the circuit to solenoid 98 is broken and the selector valve discs 95 and 96 will be moved into the illustrated and low rate position if they are not already in such positions.- flow through the normal path through conduit I1, space 29 and conduit 23 to low rate nozzle I, while flow from conduit I3 to the high rate nozzle 2 will be cut of! by valve disc 95 and flow from the conduit 93 to the high rate nozzle will be cut off by the valve disc 19. With the handle H4 in low rate position, the contact I94 is disengaged from brushes I93 and I95 so that the circuit to'the rate selector switch I91 is broken and no circuit to either solenoid 1| or 14 can be established by this means.

The rate selector means may be manually operated by remote control, if desired. For example, a push button switch I 61 may be connected as shown in Fig. 2 to the wires 8| and IM so as to control the energization of solenoid 98 in the same manner as thermostat 99 and independently thereof. The solenoid 98 and rate selector would ordinarily be located on the .burner in the cellar and-the switch I 61 may be located at any convenient point in some one of the rooms being heated while as before stated thermostat 99 may be outdoors. 1

Other forms of automatic control may be used in place of thermostat 99, if desired. Some other useful forms of automatic controls are suggested in my copending application Serial No. 698,714, filed September 23, 1946, and others will readily occur to those skilled in the art. The present invention in its broad aspect, is independent of the particular means employed for operatingthe rate selector and I have shown specific ones for their specific advantages. The invention broadly provides a normal firlng rate selector means, which may be operated either manually or automatically, as suggested in Fig. 2 by the controls I81 and 99, respectively, and an emergency firing rate selector means for use in an emergency, when one of the nozzles fails and for any reason cannot be used, to change over to the other nozzle and temporarily disconnect the normal firing rate selector until a service man can. be reached to cure the trouble and put the system back in operation under the normal firing rate selector control.

The nozzles, ignition electrodes and burner thermostat switch may, for example, be mounted as shown in Figs. 4,, and 6. A support I21, preferably of suitable molded insulating material, is supported within the outlet end of the air tube 4 and spaced from the peripheral wall of the latter by three legs I28 (Fig. 5). The nozzles I and 2 are arranged side by side in closely adjacent relation. They are secured one to each of the outlet ends of their respective oil supply conduits 23 and 24. The terminal portion of Oil .will then cheques 19 vertical plane passing centrally between the axes of these nozzles. Each electrode is suitably fixed in aninsulating tube I39 (Figs. 4 and 5) and these tubes are suitably secured, as by set screws I3 I (Fig. 5) to the support I21.

1 The burner thermostate 9| is in the form of a axis in the aforesaid plane. This thermostat surrounds a stud I32, fixed at itsinner end to the support I21 as indicated in Fig, 4. The outer .shown in Fig. 6. Pivotally mounted at a point intermediate its ends on a stud I36 is a switch lever I31 of insulating material which carries a conducting piece I 38, adapted to engage and electrically interconnect the contacts 88 and 89. These contacts are mounted on spring fingers I39 and I49, molded in the support I21 and having prong extensions HI and I42 for connection as by an attachment plug (not shown), to the wires 81 and 99, respectively, heretofore described. The switch arm I31 is located within a recess in the bottom of the support I21, such recess being closed by a cover I 43 suitably secured to the support. The switch arm is movable between the limits defined by the abutment of a projection I44 with the upper and lower walls of a recess I45 (Fig. 6) in support I21. The outer end of the switch lever carries a spring-pressed pin I46 which bears on the outer end face of the cup I34. Thus, when the latter is turned in the direction of the arrow shown in Fig. 6, the switch lever will be turned clockwise to carry conducting piece I38 out of engagement with the contacts 88 and 89. Clockwise movement of the switch lever will continue until projection I44 is arrested by abutment with the upper wall of recess I45. Then, the cup will continue to turn as the thermostat 9i becomes increasingly hotter; the friction drive of pin I46 on cup I34 providing for the necessary slip between the parts. On the initial partof the return movement of thermostat 9|, when it commences to cool, the lever I31 will be moved to reconnect the contacts 88 and 89 and then it will continue to move until arrested by the abutment of projection I44 with the lower wall of recess I45. Thereafter, the cup I34 will continue to turn, without moving the switch lever, until it becomes thoroughly cooled. The contact bearing fingers I39 and I49 will fiex by continued movement of the switch lever after the contacts 88 and 89 have been engaged by conductor I38. Consequently, when the thermostat 9i heats up, the contacts 88 and 89 will not be immediately disconnected on the first motion of the thermostat. A predetermined amount of motion of the thermostat, requiring a predetermined time in-- terval for its accomplishment, is'necessary before the contacts 88 and 89 become disconnected;

The unit, comprising the support I21, nozzles I and 2, ignition electrodes 69 and. 6I,"an 'd,the burner thermostat 9|, and its switch are 'slidably mounted in the burner 4, the outer ends of'pin's I28 sliding on the inner peripheral wall of, tube 4. Attached to the support I21 are two rods I 41 (Fig. 6) which extend rearwardly of the air 31 tube and may beheld in place after the manner disclosed in the Smith and Duemler patent, No. 2,066,806, dated January 5, 1937. The arrangement enables the aforesaid unit to be withdrawn from the rear end of the air tube, when open, by pulling on the rods I41. These rods may also carry a suitable air director, such for example as the one shown in said patent. Since the forward ends of rods I41 are threaded and the support I21 is held in place by nuts I66, the

support may be adjusted along these rods to change its position longitudinallyof the air tube.

Fig. 3 shows one way of mounting the motor 38, fan 26 and oil pump 5. One end of the motor is suitably fixed to one end face of the fan casing 21 and the fan 26 is fixed directly to the inner end of the armature shaft I50. From the other end face of the casing 27 two parallel arms i5I extend and their outer ends are interconnected by an integral end wall I52 in which the pump is mounted and to which it is suitably secured. The cut off valve 1 and the by-pass valve 6 are preferably incorporated in the same casing with the pump, as indicated in the case of valve 7 and as more particularly shown for example in Patent No. 2,090,035 to Fellows, dated August The pump 5 is preferably driven from motor 38 through a transmission which includes a centrifugal clutch after the manner disclosed in my copending application Serial No. 672,106, filed May 24, 1946. The motor shaft I50 is connected by a flexible coupling I53 to an intermediate shaft- The air shutter 29 and the means for adjusting it for low rate and high rate operation and for shifting it from low to high rate position and vice versa have, for the most part, been described heretofore. It remains to be pointed out that the shutter is supported from the screw 32, on

which it is threaded, and that this scr ew has unthreaded, plain cylindrical portions, which are mounted for longitudinal sliding movement as well as rotary movement, one in a bearing I56 on the fan casing 21, one in a bearing I59 on the end wall I52 and one in a bearing in the end member I60, by which the cylinder 33 is supported from the end bell portion of the hollow housing 30. The shutter is held from rotating, when screw 32 is turned, by a stud I6l fixed to the end wall I52 and projecting inwardly into the hollow housing 30 and passing freely through a hole in the lower portion of the shutter.

The hollow housing 30, in the form shown in Fig. 3,is made up in two semi-cylindrical sections I62 and I63 and an end bell section I64, all of sheet metal and suitably connected to the arms I5I. The end bell I64 preferably encloses most of the pump 5 and the casings for valves 1 and 9. The air inlets 3| are preferably provided in the lower semi-cylindrical section I63.

It is desirable to provide means in the burner for the admission. of excess air during the starting and stopping periods of the burner. For this purpose, the drum element I56 of the centrifugal clutch is provided on its outer periphery with fan blades I65 which rotate in a central hole I66-in the shutter. The construction is as shown in Fig. 6 of my second-named copending application. Briefly when .the clutch fan is at rest, the spaces between the fan blades I65 provide air inlets to supplement the main inlet between the shutter 23 and the adjacent wall of fan casing 2'1. Accordingly, when the motor 38 and fan 26 start up, extra air is drawn in through these additional air inlets until the clutch elements engage and drive the pump together with the fan on the clutchelement I56. Then, this fan I65 acts to force air out of the inlet 28 through the hole I66 in a direction opposite to that of the flow during the starting period when the fan was stationary. The screw 32 is adjusted to adjust the shutter 29 when the burner is in normal operation to secure the desired 'rate of air flow. Then, when the burner is started, the effective area of the air inlet will be increased as above explained. The same result follows during the stopping period. As soon as the clutch elements I55 and I56 disengage, the fan I65 stops and air is drawn in through the center hole I66 as well as around the periphery of the shutter. This excess air arrangement obviously will function as described with the high rate operation as well as with the low rate operation. The shutter position for both low rate and high rate operation may be adjusted with precision. one by turning the screw 32 and the other by turning the screw 31 to adjust stop 36 (Fig. 3).

In operation, the burner is started and stopped under the usual thermostat control and operates at a high or a low rate according to the setting of the normal firing rate selector means. Such means may be the manually operated valve II of Fig. 1; the electromagnetically operated valve 95. 66 of Fig. 2, whether controlled automatically, as by the thermostat 96, or manually by remote control, as by the push button switch I61 or by any other suitable means, Oil is emitted from one nozzle or the other in an atomized spray, mixed with air and the combustible mixture ignited by the spark from the electrodes 60, 6I all in the usual and conventional way, the air supply being varied automatically by the shutter mov ing means 33, 34, 35, to appropriately increase or decrease the rate of air supply as the rate of oil supply is respectively increased or decreased.

The invention is characterized in one respect by means which insure that the nozzle not selected for operation by the normal firing'rate selector means is operated for a small part of each cycle of operation of the burner. With the normal firing rate selector set for low rate operation, as shown, when the burner is started up, the solenoid II will be energized, drawing valve 69, I0 to the left and holding it there for a predetermined time interval. Valve 69 will shut off the oil supply to conduit 23 and low rate nozzle i and valve 10 will connect the oil supply conduit 93 with conduit 92 and thus to conduit 24 and the high rate nozzle 2. At the same time valve 16 will cut oif the suction connection of conduit 64 to conduit 62 and some of the oil supplied to conduit 92 will pass by conduit 62 to the cylinder 33 to cause shutter 29 to be moved to its high rate position. Operation at a high firing rate will continue until the thermostat 9| causes the circuit to solenoid 'II to be opened. Valve 69, I0 is then moved back by its spring into the illustrated position, causing the oil supply to be cut of! from nozzle 2 and connected to nozzle l for 13 firing at the low rate. Also, the oil supply to cylinder 33 is cut ofi and the latter is connected to the suction side of the pump, whereby shutter 29 is moved back to its low rate position by spring 35, Fig. 3. If the normal firing rate selector is set for high rate operation, the solenoid 14 will be energized when the burner starts and valve I2, 13 will be drawn to the right. Valve I3. will then shut off the oil supply to conduit 24 and thus to the high rate nozzle 2. Valve I2 will connect oil supply pipe 93 to conduit 94 and thus to conduit 23 and low rate nozzle I. The air shutter 29wil1-remain in low rate position be-' cause oil supply to cylinder 33 is cut oil by valve I3.

It is to be noted that when the burner stops, the pressure in the system will drop to atmos pheric and thus, even if the shutter 29 is in high rate position, when the burner is running, it will be moved to low rate position, when the burner stops, even though the normal firing rate selectorv operated for a short period at the start of each cycle of operation of the burner. Such nozzle is operated for only a small part of each cycle of operation of the burner but such part need not necessarily occur at the start of each cycle although that happens to be a convenient way in the particular embodiments of the invention herein illustrated.

The operation of each nozzle during part of each cycle of operation of the burner helps to keep it in condition and reduce the likelihood of the nozzle plugging due to carbonization as heretofore described. However, if a stoppage of one nozzle does occur or if flow thereto is prevented in any way, so that the burner cannot operate as intended, the hand-operated firing rate selector means of Fig. 2 may be utilized to connect the other nozzle for operation and temporarily disable the normal rate selector means.

. the L position, the contact I will be disengaged from brushes I03 and I05, and this breaks the circuit to solenoid 98, causing the normal rate selector to move back to low rate position. If the burner is operating at a low rate and fiow from nozzle l ceases, the handle IN can be turned to H position. This will cause contact IM to connect the brushes I23 and I24 and energize the solenoid II. The circuit to solenoid II will be maintained as long as the room thermostat switch 39 is closed because the thermostat switch 88, 89 is shunted out, when the brushes H6 and I I! are connected by the contact I23. The energization of solenoid II shifts valve 69, 10 to the left, cutting off the oilsupply to conduit 23, and thus to nozzle I, and closing the suction connection to cylinder 33. At the same time oil is admitted from conduit 93 to conduit 92 and thus to the high rate nozzle 2 and cylinder 33. The burner will then operate at the high rate as long as the thermostat switch 14 39 remains closed and handle H remains in its high rate position. This arrangement is important and advantageous in house heating systems where there is no fireman in attendance. If the burner fails to operate at the desired rate, operation can be continued at the other rate until a service man can be reached to cure the trouble.

In this aspect of the structure, the two nozzle combination in one burner is useful apart from the main purpose of varying the firing rate.

This isbecause apart from the respective firing rates of the two nozzles, one nozzle always functions 'as a standby means for continuing the burner operation in the emergency of the other nozzle being plugged and inoperative for. that reason. In oil burners used to heathouse's the custom of using a single nozzle burner runs the HOZZIG.

With regard to a general aspect of this invention it should be noted and emphasized that it is a new and useful construction which is of the pressure atomizing type for house heating systems, the new burner being particularly constructed and arranged to retain the extremely important advantages of the routine prior .art oil burner of this type for house heating purposes and add the advantage of providing for a variable firing rate not only without interference but with cooperating advantages, as for example having a standby nozzle for operation at the mere turning of a switch or handle in an emergency of a. plugged nozzle.

Among the. advantages in the oil pressure atomizing class that this invention retains is that of intermittent on and oil operation of the burner giving intervals of complete burner shut down without any pilot fire in operation. It has been found to be a more efficient way to use oil for house heating and for that reason is by far the widest used as compared ,to variable firing rate oil burners of other than the oil pressure atomizing type. For example, oil burner types which have been in competition with the on and off oil pressure atomizing burners have offered the householder the advantage of a variable firing rate burner per se over many years but the disadvantages which have accompaniedthat one advantage have been too great and the competitive history shows the fact that advantages of the on and oil operation of the. routine oil pressure atomizing burner, even without a variable firing rate, has forged far ahead statistically in the competition as well as from an engineering view point based on experience in the economical use of oil for house heating.

Thus the problem of this invention is related very closely to the object of retaining all the advantages of the particular type of burner for house heating and improvingtha't type to'give it the several additional advantages which have been disclosed above in relation to the best way of constructing and operating the new burner as far as I now know.

Having disclosed my invention, I claim:

- l. A variable-firing-rate oil burner of the pressure atomizing type for house heating systems,

having in combination, a motor, an air fan, an oil aaoaooa for selectively connecting said oil conduits to the pump to secure high or low rate firing during cycles of operation of the burner, and means automatically operable once during each cycle of operation of the burner and for a port-ion only of such cycle to prevent the flow through the selected oil conduit and supply oil to the other oil conduit.

2. A variable-firing-rate oil burner of the pressure atomizing type for house heating systems, having in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor, means for starting and stopping said motor to produce a cycle of operation, an air conduit connected to receive air from the fan, a pair of oil conduits extending within said air conduit, a pressure atomizing nozzle attached to the end of each oil conduit, a valve for selectively connecting said oil conduits to the pump to secure high or low rate firing during cycles of operation of the burner, and means including a second valv'e automatically operable once during and for a small portion of each cycle of operation of the burner to prevent the fiow through whichever oil conduit is connected to the pump by the first-named valve and supply oil to the other oil conduit.

3. A variable-firing-rate oil burner of the pressure atomizing type for house heating systems, having in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from the motor, means for starting and stopping said motor, to produce a cycle of operation, an air conduit connected to receive air from the fan, a shutter to control the rate at which air is supplied through said air conduit, a pair of oil conduits extending within said air conduit, a pressure atomizing nozzle attached to the end of each oil conduit, firing-rate selector means for connecting one or the other of said oil conduits to the pump for high or low rate firing, means operatively connected to said selector means for adjusting said shutter to increase and decrease the rate of air supply as the firing rate is respectively increased or decreased, and means automatically operable once during each cycle of operation of the burner and for a relatively short portion of such cycle to switch the oil supply from the oil conduit connected to the pump by said selector means to the other oil conduit and simulof air supply in proportion to the fuel rate,

4. A variable-firing-rate oil burner of the pressure atomizing type for house heating systems, having in combination, a motor, an air fan, an oil pump, a transmission for driving the fan and pump from-the motor, means for starting and stopping said motor to produce a cycle of operation, an airconduit connected to receive air from the fan, a pair of oil conduits extending within said air conduit, a pressure atomizing nozzle attached to the end of each oil conduit, firingrate selector means for connecting one or the other of said oil conduits to the pump for high or low. rate firing, and means independent of said selector means and operable each time said motor is operated to momentarily prevent the flow to the oil conduit selected by said means and i6 momentarily connect the other oil conduit to said pump.

5. In an oil burner of the type wherein a fan and a pump driven by an electric motor respectively supply air and oil for combustion and two oil atomizing nozzles are connectible to said pump in different ways to secure two different firing rates, said fan including a casing having inlet and outlet openings, the combination of an adjustable shutter to control one of said openings, mechanism to adjust said shutter comprising, a rod passing through and having a screw thread engagement with the shutter, bearings in which said rod is mounted for rotatable and axially slidable movement, stationarily-supported stops for limiting the axial sliding movement of said rod in both directions, yieldable means for holdin said rod against one of said stops to locate said shutter in position for one firing rate, a hydraulic power cylinder, and a piston in said cylinder operatively connected to said rod and operable by oil under pressure to move the rod axially against the force of said yieldable means against the other of said stops toloCate the shutter in position for the other firingrate, said rod while engaged with one of said stops being rotatable for a precision adjustment of the position of the shutter for one firing rate, the other of said stops being mounted in its support with a threaded engagement and being rotatable to effect a precision adjustment of the position of the shutter for the other firing rate, an oil conduit system between the pump and nozzles, and a firing rate selector valve in said system movable from one position to another position to select one or the other firing rate, said selector valve being operable when moved into position for the second firing rate to connect said cylinder to the pressure side of said pump to receive oil under pressure therefrom and cause the shutter to be moved from one stop to the other into position for the second firing rate.

6. In an oil burner of the type wherein a fan and ,a pump driven by an electric motor respectively supply air and oil for combustion and two oil atomizing nozzles are connectible to said pump in difierent ways to secure two different firing rates, said fan includin a casing having inlet and outlet openings, the combination of an adjustable shutter to control one of said openings, mechanism to adjust said shutter comprising, a rod passing through and having a screw thread engagement with the shutter, hearings in which said rod is mounted for rotatable and axially slidable movement, stationarily-supported stops for limiting the axial sliding movement of said rod in both directions, yieldable means for holding said rod against one of said stops to locate said shutter in position for one firing rate, a hydraulic power cylinder, and a piston in said cylinder operatively connected to said rod and operable by oil under pressure to move the rod axially against the force of said yieldable means against the other of said stops to locate the shutter in position for the other firing rate, said rod while engaged with one of said stops being rotatable for aprecision adjustment of the position of the shutter for one firin rate, the otherof said stops being mounted in its support with a threaded engagement and being rotatable to effect a precision adjustment of the position of the shutter for the other firing rate, an oil conduit system between the pump and nozzles, and a firing rate selector valve in said system movable from one position to another position to select one or the other firing rate, said selector valve being operable when moved into position for the second firing rate to connect said cylinder to the pressure side of said pump to receive oil under pressure therefrom and cause the shutter to be moved from one stop to the other into position for the second firing rate, and operable when moved into position for the first firing rate to connect said cylinder to the suction side of said pump.

7. In an oil burner of the type wherein a fan and pump driven by an electric motor respectively supply air and oil for combustion and two oil atomizing nozzles are connectible to said pump in different ways to secure two difierent firing rates, said fan including a casing having inlet and outlet openings, the combination of an adjustable shutter to control one of said openings, mechanism to adjust said shutter comprising, a rod passing through and having a screw thread engagement with. the shutter, bearings in which said rod is mounted for rotatable and axially slidable movement, stationarily-supported stops for limiting the axial sliding movement of said rod in both directions, yieldable means for holding said rod against one of said stops to locate said shutter in position for one firing rate, a hydraulic power cylinder, and a piston in said cylinder operatively connected to said rod and operable by oil under pressure to move the rod axially against the force of said yieldable means against the other of said stops to locate the shutter in position for the other firing rate, said rod while engaged with one of said stops being rotatable for a precision adjustment of the position of the shutter for one firing rate, the other of said stops being mounted in its support with a threaded engagement and being rotatable to efiect a precision adjustment of the position of the shutter for the other firing rate, an oil conduit system between the pump and nozzles, and a firing rate selector valve in said system movable from one position to another position to select one or the other firing rate, yieldable means for holding the selector valve in position for one firing rate, and an electromagnet operable when energized to move the selector valve against said yield- REFERENCES CITED The following references are of record in the file of this patent:

UNITED PATENTS Number 'Name Date 1,637,820 Hawkins Aug. 2, 1927 1,976,097 Sharp Oct. 9, 1934 2,315,412 Galumbeck Mar. 30, 1943 2,403,230 Nagel et a1 July 2, 1946 

